#include <iostream>
#include <memory>
using std::cout;
using std::endl;
using std::shared_ptr;
using std::unique_ptr;

class Point
: public std::enable_shared_from_this<Point>
{
public:
    Point(int x,int y)
    : _ix(x)
    , _iy(y)
    {}


    //(1)
    /* Point * addPoint(Point * pt){ */
    /*     _ix += pt->_ix; */
    /*     _iy += pt->_iy; */
    /*     return this; */
    /* } */


    //(2)
    /* shared_ptr<Point> addPoint(Point * pt){ */
    /*     _ix += pt->_ix; */
    /*     _iy += pt->_iy; */
    /*     //创建的匿名的shared_ptr和sp共用一个裸指针 */
    /*     return shared_ptr<Point>(this); */
    /* } */


    //(3)
    shared_ptr<Point> addPoint(Point * pt){
        _ix += pt->_ix;
        _iy += pt->_iy;
        return shared_from_this();
    }


    void print() const{
        cout << "(" << _ix
            << "," << _iy
            << ")" << endl;
    }
private:
    int _ix;
    int _iy;
};

void test0(){
    shared_ptr<Point> sp(new Point(1,2));    
    shared_ptr<Point> sp2(new Point(3,4));

    //(1)如果使用sp的裸指针创建sp3
    //那么就是sp3和sp共同管理一个Point,却没有通过shared_ptr的复制
    //
    //(3)不存在任何的非法的使用同一个裸指针创建多个shared_ptr的情况
    shared_ptr<Point> sp3(sp->addPoint(sp2.get()));
    cout << "sp3 = ";
    sp3->print();
}



int main(void){
    test0();
    return 0;
}
